Grid reliability · 2024 · 16 reporting utilities

Power outages in Illinois

The utilities that reported here serve 5,831,894 customers between them, not the whole state. Weighted by customer count, they averaged 59 min without power in an ordinary year and 2.6 hr once major events are counted. Each figure comes only from the filers that published it, and the counts are below.

What it means

Why there are two numbers

Across the utilities that filed both figures, major events account for 63% of the outage time Illinois recorded once they are counted: 2.7 hr against 59 min without them, a factor of 2.7×. Solar panels alone do not help during an outage, because a grid-tied array shuts down when the grid does, so riding through one is a battery question. This figure will not answer it: it is an annual average across a utility’s customers, not the length or the load of any single outage. What it does say is how much of the outage time here arrives with major events rather than on ordinary days.

The comparison is drawn from the 13 utilities that filed both figures of the 16 reporting here, so both sides of the ratio describe the same set of customers. The two headline figures above are averaged over everyone who filed each one, so dividing them would not give this number.

Ordinary year59 min50 of 51 jurisdictions, longest first · 13 filings

With major events2.6 hrStorms, ice, and fires included as filed · 16 filings

Interruptions a year0.6×Ordinary year; 0.8× with major events

The bill sideWhat solar offsetsRates and modelled output by utility

The utilities behind the average

Each of Illinois’s figures is a customer-weighted average of the filings that carried that metric, not of the table as a whole: the ordinary-year average is built from 13 filings and the storm-inclusive average from 16 filings, out of 16 filings that published an outage figure at all. Those two sets are not the same utilities, so the two columns cannot be compared filer by filer. A utility that filed without publishing a metric, or whose two major-event variants contradicted each other, is absent from that metric rather than counted as zero.

Reported interruption metrics for 2024, largest utility first.
Utility	Customers	Ordinary year	With major events	Interruptions
Commonwealth Edison Co	4,229,904	36 min	2.2 hr	0.5×
Ameren Illinois Company	1,249,900	2.0 hr	3.7 hr	0.9×
MidAmerican Energy Co	85,293	2.9 hr	5.9 hr	1.4×
City of Naperville - (IL)	62,990	not reported	25 min	not reported
Corn Belt Energy Corporation	37,191	2.5 hr	5.2 hr	4.7×
Southwestern Electric Coop Inc - (IL)	25,284	4.4 hr	5.1 hr	1.8×
Southeastern IL Elec Coop, Inc	25,005	2.3 hr	10 hr	1.5×
Jo-Carroll Energy, Inc	20,356	49 min	67 min	0.4×
Tri-County Electric Coop, Inc (IL)	16,708	64 min	6.2 hr	0.7×
Egyptian Electric Coop Assn	15,824	not reported	2.1 hr	not reported
Eastern Illinois Elec Coop	13,503	3.2 hr	4.5 hr	1.7×
Menard Electric Coop	11,141	113 min	2.8 hr	1.3×
City of Batavia - (IL)	10,737	41 min	46 min	0.4×
Rock Energy Cooperative	10,558	16 min	18 min	0.3×
City of Geneva- (IL)	10,153	83 min	3.3 hr	0.6×
Rochelle Municipal Utilities	7,347	not reported	22 min	not reported

What this page is not

It is a state average of utility filings, not a measurement at any address. Each filing is itself an average over a whole service territory, so a rural feeder and a downtown network arrive here as one number, and nothing in this dataset says how far an individual address sits from it. Nothing here predicts a future year either, and a single severe storm can move a utility’s figure by an order of magnitude.

The methodology page states the sources, the definitions, and the limits. Back to the Grid Reliability Index

Source: U.S. Energy Information Administration, Form EIA-861 reliability file, data year 2024, covering 2024-01-01 through 2024-12-31. The snapshot covers no later period.